A filter (10) has a serial arm resonator (s1) connected to a path connecting an input-output terminal (11m) and an input-output terminal (11n), and has parallel arm resonators (p1, p2) that are connected between the same node (x1) on said path and ground, wherein: the parallel arm resonator (p2) has a resonant frequency higher than that of the parallel arm resonator (p1); the parallel arm resonator (p2) has an anti-resonance frequency higher than that of the parallel arm resonator (p1); and the parallel arm resonator (p2) has an IDT electrode (131) for exciting acoustic waves, but has no reflector.